Under the ThumbnailSelectorField project, in the context menu of the References folder, click Add Reference...

Browse to the bin folder of your SitefinityWebApp project and select the following assemblies:

Telerik.OpenAccess.dll

Telerik.Sitefinity.dll

Telerik.Sitefinity.Model.dll

Telerik.Web.UI.dll

Build your solution and restart the application.

If prompted, save the solution file in the root application folder.

Close Visual Studio.

Run the project and create a custom field for a chosen module using procedure Create a new custom field.

In Type, select Short Text.

In Name, enter Thumbnail

In Interface widget for entering data, select Custom…

In Type or Virtual path of the custom widget, enter Telerik.Sitefinity.Samples.SimpleImageField

Upload some images and if there are no albums created, create albums.

Edit the widget template that you are going to use to display the items.
For example, if you want the images to be displayed with the news items in list mode, edit the News – list widget template that you will use. For more information, see Create and edit widget templates.